A flame retardant associated with hyperthyroidism in cats

Feline hyperthyroidism is the most common endocrine disorder in older cats. And since the first case was diagnosed in 1979, the prevalence of the disease has been steadily increasing. Researchers have linked this to the introduction of household flame retardants onto the market. And with good reason. In the mid-1970s, around the same time that the first cases of feline hyperthyroidism began to appear, polybrominated diphenyl ethers (PBDEs) were introduced into textiles, polyurethane foam, plastics, and electronic equipment for their flame-retardant properties. But over the years, the health effects of these molecules have come under scrutiny. In 2004, U.S. manufacturers began voluntarily phasing out these flame retardants for environmental and health reasons. Numerous studies seem to classify PBDEs as endocrine disruptors. “Eliminate” may not be the exact word, since in reality, the molecules are being replaced by alternatives. Organophosphorus esters (OPEs), such as tris(1,3-dichloroisopropyl) phosphate (TDCIPP), are added instead. And this is despite studies indicating that these compounds are just as disruptive to the body. This is particularly true for cats. Previous research has indeed suggested a link between PBDE levels and feline hyperthyroidism. However, until now, OPEs had never been examined in this context. A new study in ACS’s *Environmental Science & Technology* corrects this oversight and highlights the role of OPEs in the development of feline hyperthyroidism using silicone collars worn around the animals’ necks. Silicone is capable of capturing volatile and semi-volatile organic compounds. It can therefore be used to monitor exposure to environmental chemicals. Worn around the necks of cats for 7 days, the silicone medallions allowed researchers to assess the exposure of hyperthyroid and non-hyperthyroid cats to various flame retardants, including OPE. Result: The silicone around the necks of cats with hyperthyroidism contained higher levels of TDCIPP. And in non-hyperthyroid cats, exposure to TDCIPP can be correlated with serum concentrations of a hormone that is overexpressed in hyperthyroidism. This exposure to high concentrations of TDCIPP has been linked to the use of air fresheners, homes built since 2005, and cats that prefer to nap on upholstered furniture.